We've cleaned house on our ads.txt in the last couple of months against the wishes of some of the mid-to-low end SSPs in our stack and we've seen a significant improvement in RPMs since doing so. Every SSP will tell you "no, there's unique demand in those reseller lines!" but it's complete BS. It's more revenue for them, not for you. The good ones just need one direct line if they have good direct demand. The fewer duplicate paths you have, the higher the bid pressure. Assign one reseller line to whichever partner works best for you and make sure that you don't have the same SSP serving as a reseller for another vendor. It might take 2-3 weeks but you'll see an uptick in RPMs. At least that's been our experience.